The present invention relates to a method of forming an etching mask pattern and, more particularly, to a method of forming an etching mask pattern from developed negative and positive photoresist layers, in which it can reduce a pattern pitch through exposure and development according to a combination of a chemically amplified negative photoresist and a chemically amplified positive photoresist.
As semiconductor products are miniaturized and highly integrated, there is a growing interest in patterning technologies for forming a pattern in order to improve a new function of devices. Current patterning technologies with a high integration level have been developed as nuclear technologies of semiconductor fabrication, and a photolithography process is generally used. In this photolithography process, a photoresist (PR) (that is, a chemical material that reacts according to whether light is irradiated) is coated to form a photoresist layer. The photoresist layer is exposed and developed, thus forming an etching mask pattern. The underlying layer is selectively etched and patterned using the formed etching mask pattern.
In general, the process capability limit (resolutions) of a photoresist layer exposure equipment used at the time of patterning is represented by the half pitch, which is half the pattern pitch defined as the sum of a width of the line pattern and a width of the space adjacent to the line pattern.
The resolution of exposure equipment that has been developed so far is 45 nm on the basis of the half pitch. It is necessary to reduce the pattern pitch or the half pitch in order to increase a net die.